Laser, Waterjet and Plasma Cutting

Distinguish a thermal cut from an erosive cut

Laser and plasma use concentrated heat. Waterjet uses mechanical energy. A heat-affected zone (HAZ) is material beside a cut whose properties or structure have changed from heating without being melted away.

Laser cutting concentrates light into a small region

A focused laser beam supplies thermal energy; cutting gas commonly helps remove material. Laser cutting is a candidate for fine profiles in sheet material. Metals, wood and selected plastics require suitable laser systems; a machine that cuts acrylic is not automatically a metal cutter.

A narrow kerf and fine detail are possible, particularly in thinner material. Edge finish, taper and dimensional accuracy depend on material, thickness, focus, gas and cutting speed. Melting, discoloration or charring may affect the edge. Do not assume the HAZ is zero.

Waterjet cuts soft materials; added abrasive cuts hard materials

Pure waterjet uses a high-speed water stream for materials such as foam, rubber and other soft sheet. Abrasive waterjet adds hard particles to erode metals, stone, non-tempered glass and many ceramics. Electrical conductivity is not required.

Waterjet normally creates no thermal HAZ. It is a candidate for thick stock or a heat-sensitive edge, but thickness still affects speed and cut quality. Taper, where the cut width changes through the thickness, and striations, visible lines down the cut face, can limit accuracy and finish. Slower quality cuts may reduce these effects. Brittle edges may chip and need finishing.

Identify the glass type before choosing a process: tempered glass is not a candidate for ordinary waterjet cutting. A no-HAZ process is not a promise of no mechanical damage.

Plasma is a thermal cutting candidate for conductive metal

A plasma cutter uses an electric arc through ionized gas to melt metal; the gas stream expels it. The work must conduct electricity. Steel, stainless steel and aluminum are candidates; ordinary glass and wood are not.

Plasma often suits productive plate cutting where its edge quality meets the drawing or later machining is planned. Compared with a fine laser cut in thin sheet, small details can be harder to hold. Edge bevel, attached solidified metal (dross) and a HAZ may need attention. Equipment and thickness determine actual capability; plasma is not automatically a rough-only process.

Continue with Selecting a Material-Removal Process. Safety references: Machine Hazards and Housekeeping, Electrical Safety, Fire Safety and Chemicals and Safety Data Sheets.